Pancreatic endotherapy has been used for years for treatment of several types of pancreatic disorders including but not limited to chronic pancreatitis, idiopathic acute recurrent pancreatitis, and many such others.
Normally, inside the human body the pancreas is connected to the duodenum via the pancreatic duct. The pancreatic duct abuts the sphincter of Oddi, which connects the pancreatic duct to the duodenum. The pancreatic duct delivers to the duodenum pancreatic fluids required for metabolism. In various pancreatic disorders, pancreatic tissues may swell or increase abnormally thereby constricting the pancreatic duct and obstructing flow of pancreatic fluids into the duodenum. Such obstructions could lead to various complications including those arising from the accumulation of pancreatic fluids inside the pancreatic tissue or the pancreatic duct. In such cases, an intraluminary prosthesis, such as a stent, may be used for treatment of the obstructed pancreatic duct. The stent provides an outwardly-directed radial force that opens the constriction of the pancreatic duct thereby allowing pancreatic fluid to flow into the duodenum. In some cases, at least a portion of the stent is placed proximal to the sphincter of Oddi and adjacent to ampulla of Vater near and inside head region of the pancreas in a patient's body.
Intraluminal stents within the pancreatic duct are associated with several drawbacks including stent migration and blockage of side branches of the pancreatic duct. Blockage of pancreatic duct side branches can impede flow of pancreatic fluids and result in chronic pancreatitis. Some pancreatic stents are polymer tubes that have side holes helically placed along a length of the stent. The side holes allow pancreatic fluid to flow into the lumen of the stent thereby reducing the incidence of side branch occlusion while still allowing for stent removal at a future time. An example of a intraluminal pancreatic stent is provided in U.S. Pat. No. 6,132,471, which is incorporated herein by reference.
Recently physicians are looking to metal stents for use in the pancreas. Expandable metal stents provide substantially consistent outward radial force over time, which allows the stent to expand as duct constriction is relieved. In this way, metal stents avoid the need to exchange the stents multiple times, each time for a progressively larger diameter stent, until the desired dilation of the pancreatic duct is achieved. Another benefit of metal stents is a greater patency rate.
A concern with metal stents is that surrounding tissue may grow into the stent, complicating stent removal and compromising the stent lumen. For this reason metal stents are often coated with a polymeric covering that reduces growth of host tissue into the interstices of the metal stent. Coated metal stents allow for easier and less traumatic stent removal. Unfortunately, coated stents are more susceptible to stent migration, which can result in the stent exiting the treatment site.
Coated stents are also more likely to occlude pancreatic fluid flow within side branches of the pancreatic duct. Pancreatic fluid flows to the duodenum through a network of branching upstream ducts that converge into a central pancreatic duct. Coated stents placed in a downstream pancreatic duct may block the mouth of an upstream tributary duct that empties into the downstream duct. In this way, a coated stent could dam an upstream network of ducts. Impeding the flow of pancreatic fluid can harm the pancreas and result in pancreatitis.
Thus, there exists a need for a stent with an additional drainage system to avoid occlusion of upstream ducts while reducing the likelihood of stent migration.
Without limiting the scope of the invention, a brief summary of some of the claimed embodiments of the invention is provided below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention can be found in the detailed description of the invention.
A brief abstract of the technical disclosure in the specification is provided as well for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims.
All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.